Figure 5.

Binding interface of the Sem-5 C-SH3 domain (ribbon) with the Sos peptide (gold thick line). Solvent-exposed Pro residues at the third and sixth positions that are mutated in this study to Ala and Gly residues are labeled. Residues highlighted in green (F163, Y207, N206, and W191) form intermolecular H-bonds with certain Os (red) in the backbone of the Sos peptide in the crystal structure. Some residues with noticeable chemical shift changes are in the RT loop (Q168 and E169, in blue).